Icom ID-51E

• 1ST IF CIRCUITS
4 - 2
1ST IF CIRCUITS
VHF BAND (108–174 MHz)
• Band A (137–174 MHz)
The RX signal from the RF circuit is applied to the 1st mixer
(Q820) and mixed with the 1st LO signal, resulting in the 46.35
MHz 1st IF signal. The converted signal is passed through the
RF SW (D820), 1st IF fi lter (FI3) and limiter (D23), and then
applied to the 1st IF AMP. (Q44). The amplifi ed signal is ap-
plied to the 2nd IF circuit, through the limiter (D22).
• Band B (108–174 MHz)
The RX signal from the RF circuit is applied to the 1st mixer
(Q830) and mixed with the 1st LO signal, resulting in the 61.65
MHz 1st IF signal. The converted signal is passed through the
RF SW (D830), 1st IF fi lter (FI880) and limiter (D880), and
then applied to the 1st IF AMP. (Q901). The amplifi ed signal is
applied to the 2nd IF circuit.
-Band A:46.35MHz-
-Band B:61.65MHz-
D22
FI3
A_LO
1st LO
1st LO
LIMIT
46.35MHz
Q44
LIMIT
D23
Q901
B_LO
61.65MHz
D880
FI880
Q811
VCO1 UNIT
Q830
D812,D831
Q801
Q820
D811,D830
LIMIT
VCO2 UNIT
D801,D820
D802,D821
To the 2nd IF circuit (Band A).
To the 2nd IF circuit (Band B).
From the RF circuit (Band A).
From the RF circuit (Band A).
From the RF circuit (Band B).
From the RF circuit (Band B).
BPF
XTALIF
AMP
IF
AMP BPF
XTAL RF
SW
RF
SW
RF
SW
RF
SW
UHF BAND (380–479 MHz)
• Band A
The RX signal from the RF circuit is applied to the 1st mixer
(Q801) and mixed with the 1st LO signal, resulting in the 46.35
MHz 1st IF signal. The converted signal is passed through the
RF SW (D801), 1st IF fi lter (FI3) and limiter (D23), and then
applied to the 1st IF AMP. (Q44). The amplifi ed signal is ap-
plied to the 2nd IF circuit, through the limiter (D22).
• Band B
The RX signal from the RF circuit is applied to the 1st mixer
(Q811) and mixed with the 1st LO signal, resulting in the 61.65
MHz 1st IF signal. The converted signal is passed through the
RF SW (D811), 1st IF fi lter (FI880) and limiter (D880), and
then applied to the 1st IF AMP. (Q901). The amplifi ed signal is
applied to the 2nd IF circuit.